1. Field of the Invention
Exemplary embodiments of the present invention relate to a method of forming an alignment layer, and an apparatus for forming the alignment layer. More particularly, exemplary embodiments of the present invention relate to a method of forming an alignment layer capable of reducing the number of steps of a photoalignment process for forming a multi-domain structure, and an apparatus for forming the alignment layer.
2. Description of the Related Art
A liquid crystal display (“LCD”) apparatus is one of the most widely used types of flat panel display apparatuses. The LCD apparatus includes two display substrates, a liquid crystal layer interposed between the two display substrates and a polarization member disposed on the outside of the display substrates. Each of the display substrates includes an electric field generating electrode such as a pixel electrode, a common electrode, etc.
The LCD apparatus may have a problem of a narrow viewing angle. In order to increase the viewing angle of the LCD apparatus, a multi-domain liquid crystal cell has been developed. Main viewing angles of pixels in the multi-domain liquid crystal cell are different from each other in order to increase the viewing angle.
In order to form the multi-domain liquid crystal cell, a method of forming a slit in the electric field generating electrode or a method of forming a protrusion on the electric field generating electrode has been devised.
However, the slit or the protrusion formed in/on the electric field generating electrode may reduce the optical transmissivity of the pixel. Therefore, in order to form the multi-domain liquid crystal cell without the slit or the protrusion, a method of forming an alignment layer having multiple alignment directions has been developed. For example, an alignment layer including polyimide is coated on a substrate, and a mono-domain structure is formed on the substrate by rubbing the entire substrate. Then, a first domain is rubbed in the opposite direction while a second domain is blocked with photoresist, so that a multi-domain structure is formed having a first domain with an alignment orientation corresponding to the rubbing in the opposite direction and a second domain retaining the alignment orientation corresponding to the original mono-domain structure.
However, there is a problem with the liquid crystal cell manufactured by the above-mentioned method in that dust or static electricity generated during the rubbing process may damage the liquid crystal cell, and thus a manufacturing yield may be reduced.
In order to solve the problem of the rubbing process, a method of photoalignment using an ultraviolet light instead of the rubbing process has been proposed. In the method of the photoalignment, a mask having a transmission portion and a blocking portion in a predetermined pattern is disposed over a substrate and an ultraviolet light is irradiated onto the substrate to form a pretilt at an alignment layer.
When four domains are formed by a conventional photoalignment method, at least four processes for the photoalignment are required. When the combination of an upper substrate and a lower substrate, each having a multi-domain alignment layer, is considered, at least eight processes for the photoalignment are required. When the steps of the photoalignment process are increased, it is necessary to additionally readjust a gap between a mask and a substrate. Further, various errors may occur in the alignment of the mask, and thus productivity may be reduced.